In an aircraft, the outer skin is spaced from the walls and ceiling of a passenger cabin (or other compartment), and the gap is at least partially filled with an insulation layer or blanket. The insulation layer is typically formed from a waterproof material and often in the form of a plurality of blankets. Conventional insulation blankets come in three separate but subsequently attached parts, a bay blanket that fits between two frame members (which form a “bay” between them), a cap strip that covers the frame members, and a return blanket. The cap strips are held to the frame members by a retaining or spring clip. Today, gaps between bay blankets and cap strips permit cabin air to reach the aircraft skin and the frame members, which become cold during flight. Liquid from moist air can condense against the cold skin and/or the cold frame members, particularly at the top of the fuselage, and freeze during cruise. During descent, this frozen liquid can thaw and drip back down towards the cabin, but because of the gaps between the bay blankets and cap strips, the liquid can sometimes seep through the gaps and into the passenger cabin, which is an undesirable result.
In addition, condensed moisture sometimes can find its way into the gaps between the bay blankets and cap strips during flight, and within folds and/or wrinkles in the blankets, for example where they are held to the frame members by the retaining clips. This condensed moisture in the gaps and/or folds is often situated near a cold frame member or cold clip (which are conventionally thermally conductive and are cooled by being in close proximity to the frame members) and also is prone to freezing during cruise and then thawing during descent, leading to liquid moisture falling into the passenger cabin.